To cross into Canada you need a passport or an enhanced drivers license (NY, Michigan, etc). I bring birth certificates (copies) for my kids. Definitely go to the Canadian side for view of the falls and fund things to do. The NY side just isn't all that great. Maid of the Mist is worth the wait time. If you are staying on the Canadian side it's only another 1.5hr to Toronto if you want to squeeze in another day trip. I adore Toronto. There's a nice theater district, great shopping, hockey museum, zoo, take in a Blue Jays game, etc. You could also day trip to Buffalo which also has a nice zoo, Albright Knox art gallery, harbor front area, to name a few.
Hotels in Niagara Fall...both NY and Canada are often on Groupon.
Mom to two amazing DDs ('07 & '09) and a fur baby.
Gluten free since Nov '11 after non-celiac gluten sensitive diagnosis. Have had great improvement or total elimination of: migraines, bloating/distention, heartburn, cystic acne, canker sores, bleeding gums, eczema on elbows, dry skin and scalp, muscle cramps, PMS, hair loss, heart palpitations, fatigue. I'm amazed.